Pest density – plant damage relationships are essential guides for decision-making in integrated pest management. In this article, we established pest density – leaf damage relationships for the ...beech leaf-mining weevil, Orchestes fagi L. (formerly Rhynchaenus fagi, Coleoptera: Curculionidae), in its invasive range of Nova Scotia, Canada. Outbreaks of O. fagi cause tree-wide leaf necrosis in American beech (Fagus grandifolia Ehrh.), which can eventually result in tree mortality. In 2014 and 2016, we collected weekly samples in stands with American beech and assessed leaves for densities during different life stages (eggs, larvae, and pupae), population proxy measures (adult feeding damage, egg slits, and larval galleries), and percent necrosis. In general, feeding damage and leaf necrosis plateaued soon after the end of budburst, but before the larval mine expanded. This strongly suggested that leaf necrosis may be linked to damage caused by adults or by mine initiation rather than that caused by larval mine expansion and gallery development. The density of O. fagi per leaf for life stages and population proxies all significantly explained ∼42%–81% of the variation in end-of-season percent leaf necrosis. Results from this study provide a variety of relationships that could be used in both short- and long-term monitoring efforts for O. fagi.
Bukva predstavlja jednu od najvažnijih vrsta drveća u Bosni i Hercegovini. Stoga, potrebno je praćenje zdravstvenog stanja bukovih sastojina i poduzimanje svih neophodnih preventivnih i represivnih ...mjera kako bi se zdravstveno stanje ovih sastojina unaprijedilo. U okviru istraživanja analiziran je utjecaj bukove skočipipe na površinu oštećenja listova na stabalcima bukve od imaga i ličinke u ovisnosti od lokacije i položaja stabalaca bukve u sastojini (svjetlo/sjena). Lokacije istraživanja su se nalazile unutar kulture smreke, visokih šuma bukve i mješovitih šuma bukve i jele sa smrekom. Bukova skočipipa predstavlja jednog od glavnih defolijatora koji se javljaju na stablima bukve. Uzorak istraživanja čine 15 stabalaca bukve, po 5 stabalaca na tri lokacije. Na svakoj lokaciji odabrana su 3 stabalca čija krošnja je bila na svjetlu i dva stabalca čija krošnja je bila u sjeni (ukupno 9 stabalaca na svjetlu i 6 stabalaca u zasjeni). Na svakom stablu pregledavana su i mjerena oštećenja od imaga i ličinke bukove skočipipe. Ustanovljeno je da prosječna površina oštećenja lista bukve od imaga je varirala od 2-4%, a ličinke od 4-8%. Statističkim analizama je utvrđeno postojanje statistički značajnih razlika u površini oštećenja lista bukve od ličinke u ovisnosti od položaja stabalaca bukve u sastojini.
The impact of beech weevil on the damaged area of beech trees from adult and larvae was analyzed, depending on the location and position of trees of beech in stand (sun/shadow). The research localities were located within the forest plantation of spruce, natural beech forests and mixed beech, fir and spruce forests. Beech weevil represents one of the main defoliators appearing on beech trees. The research sample consists of 15 beech trees, 5 trees per location, on three locations. On each location, were selected 3 trees with the crown in the sun and 2 trees with the crown in the shade (a total of 9 trees in the sun and 6 trees in the shade). On each tree were measured damages from the adult and larvae of beech weevil. It has been found that the average damaged area on beech leaf varied for adult from 2-4%, and larvae 4-8%. Statistical analysis showed a statistically significant differences in damaged areas of beech leaf from larvae, depending on the position of beech trees in the stand.
Using the Swiss Canopy Crane CO
2 enrichment facility, the beech weevil's host choice in a CO
2-enriched atmosphere and the
in situ effect of its infestation on the chemistry of host leaves were ...investigated. The fraction of infested leaves was larger on CO
2-enriched trees, suggesting that weevil impact on beech may increase as atmospheric CO
2 concentration keeps rising. Egg insertion in the central leaf vein partially interrupts phloem and xylem transport. Because of this separation between the source of photosynthates, the leaf tip, and the rest of the plant, the leaf tip becomes enriched in non-structural carbohydrates and depleted in nitrogen. Elevated CO
2 slightly enhanced non-structural carbohydrates in uninfested leaves, but exerted no further increase in infested leaf part, suggesting a saturation effect.
Mit Hilfe der, Swiss Canopy Crane’ CO
2-Anreicherungsanlage haben wir
in situ die Präferenzen der Buchenspringrüssler bei der Wahl ihrer Wirtsbäume nach CO
2-Exposition und den Einfluss ihres Befalls auf die Chemie von Buchenblättern untersucht. An CO
2-behandelten Bäumen war der Befall höher als an Kontrollbäumen. Mit ansteigender atmosphärischer CO
2-Konzentration könnte sich daher die Schadwirkung des Buchenspringrüsslers auf die Rotbuche verstärken.
Die Eiablage in der Hauptblattader hat zur Folge, dass Phloem- und Xylemtransport teilweise unterbrochen werden. Diese Unterbrechung zwischen einer Assimilatquelle, der Blattspitze, und dem Rest der Pflanze, führt zu einer Anreicherung nicht-strukturgebundener Kohlenhydrate (NSC) und einer Abnahme der Stickstoff Konzentration in der Blattspitze. Die NSC-Konzentration in nicht befallenen, CO
2-behandelten Blättern zeigte zwar eine leichte Zunahme, stieg aber in den befallenen, CO
2 behandelte Blattspitzen nicht weiter an, was auf einen Sättigungseffekt hindeutet.
Using the Swiss Canopy Crane CO2 enrichment facility, the beech weevil's host choice in a CO2-enriched atmosphere and the in situ effect of its infestation on the chemistry of host leaves were ...investigated. The fraction of infested leaves was larger on CO2-enriched trees, suggesting that weevil impact on beech may increase as atmospheric CO2 concentration keeps rising. Egg sertion in the central leaf vein partially interrupts phloem and xylem transport. Because of this separation between the source of photosynthates, the leaf tip, and the rest of the plant, the leaf tip becomes enriched in non-structural carbohydrates and depleted in nitrogen. Elevated CO2 slightly enhanced non-structural carbohydrates in uninfested leaves, but exerted no further increase in infested leaf part, suggesting a saturation effect.Original Abstract: Mit Hilfe der, Swiss Canopy Crane' CO2-Anreicherungsanlage haben wir in situ die Praeferenzen der Buchenspringruessler bei der Wahl ihrer Wirtsbaeume nach CO2-Exposition und den Einfluss ihres Befalls auf die Chemie von Buchenblaettern untersucht. An CO2-behandelten Baeumen war der Befall hoeher als an Kontrollbaeumen. Mit ansteigender atmosphaerischer CO2-Konzentration koennte sich daher die Schadwirkung des Buchenspringruesslers auf die Rotbuche verstaerken. Die Eiablage in der Hauptblattader hat zur Folge, dass Phloem- und Xylemtransport teilweise unterbrochen werden. Diese Unterbrechung zwischen einer Assimilatquelle, der Blattspitze, und dem Rest der Pflanze, fuehrt zu einer Anreicherung nicht-strukturgebundener Kohlenhydrate (NSC) und einer Abnahme der Stickstoff Konzentration in der Blattspitze. Die NSC-Konzentration in nicht befallenen, CO2-behandelten Blaettern zeigte zwar eine leichte Zunahme, stieg aber in den befallenen, CO2 behandelte Blattspitzen nicht weiter an, was auf einen Saettigungseffekt hindeutet.
The relationship between supercooling and survival of the beech leaf mining weevil,
Rhynchaenus fagi was examined in exposures at constant temperatures between +10 and −15 °C, and in cycling regimes. ...Similar observations were made on naturally overwintering field populations.
No weevil survived cooling to, or below the supercooling point. The mean supercooling point of weevils exposed to temperatures at, or below +2 °C, or sampled from the field, was consistently below −21 °C. When exposed to a constant +2 or −5 °C, mortality was low, at 10 and 12% after 168 and 126 days respectively. Mortality increased rapidly in weevils exposed to temperatures below −10 °C, with 48% survival after 112 days at −10 °C and only 25% after 84 days at −15 °C. None of the dead weevils had frozen. Periods spent at +2 °C in cycling treatments which included exposure at −10 or −15 °C, extended the duration of survival at the lower temperatures compared to constant exposures at these temperatures, but mortality was still more rapid than at a constant +2 °C. Survival of naturally overwintering insects was consistently high over three winters.
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